Apache Commons toString实用程序,仅包含具有值的字段

Question

是否有来自Apache Commons的toString实用程序,它只会在结果的toString值中包含那些非null的字段？

例如:

public class Person {
String name;
String height;
String age;
}

并创建一个具有名称和年龄的实例.然后调用该实用程序,例如:

utility.toStringNonNull(person);

将输出:

[姓名=玛丽,年龄= 28]

Answer 1

我能够通过扩展Apache的ToStringStyle类来做到这一点:

public static class TestStyle extends ToStringStyle{
    TestStyle() {//constructor is copied from ToStringStyle.MULTI_LINE_STYLE
        super();
        this.setContentStart("[");
        this.setFieldSeparator(SystemUtils.LINE_SEPARATOR + "  ");
        this.setFieldSeparatorAtStart(true);
        this.setContentEnd(SystemUtils.LINE_SEPARATOR + "]");
    }

//override this to do checking of null, so only non-nulls are printed out in toString
@Override
public void append(StringBuffer buffer, String fieldName, Object value, Boolean fullDetail) {
    if (value != null) {
        super.append(buffer, fieldName, value, fullDetail);
    } 
}

然后使用是这样的:

public static void main(String[] args) {
    Person p = new Person();
    p.setName("Tester");
    ToStringStyle style = new TestStyle();

    System.out.println("toString = " + ToStringBuilder.reflectionToString(p, style));

}

这将导致:Person @ 37403a09 [name = Tester]